DENVER — A bipartisan group of lawmakers has introduced a bill into the Legislature that would make it harder to change the Colorado Constitution. The move, they said, is necessary to discourage ballot measures that most voters do not support and cost opponents millions of dollars to defeat.

The bill, introduced late Tuesday by 37 Democrats and 22 Republicans, is aimed at such measures as the so-called bad three: Amendments 60 and 61 and Proposition 101, which would have dramatically curtailed governments’ ability to tax, spend and borrow money. All three failed by more than 65 percent of the vote.

The bill would not prevent such measures from making the ballot, but it would require a higher threshold for getting passed: 60 percent, instead of a simple majority.

Lawmakers hope that will be enough to deter people from trying to change the state’s Constitution, which has been amended about 50 times over the past three decades.

“I want to make sure that it’s something that Colorado really wants, really needs,” said Rep. Don Coram, R-Montrose. “We’ve spent a lot of money on issues over the past several years that, had they passed, would have been detrimental to Colorado.”

Like other supporters of the measure, Coram said businesses are tired of having to spend money fighting these ballot measures.

Senate President Brandon Shaffer, D-Longmont, said businesses have ponied up about $177 million in recent years doing that.

That’s why Shaffer, House Speaker Frank McNulty, R-Highlands Ranch, and other leading lawmakers decided to introduce the idea this year, to ensure it would be the first measure on the 2012 ballot. They said being first up will improve its chances of getting voter approval.

“We need to get some momentum behind what I hear all the time: Why amend the Constitution? Why make the voters have to wade through these ballots?” said Sen. Gail Schwartz, D-Snowmass Village. “We’re on the fringe on this. We’re one of the most easily amended constitution states in the nation. We’re kind of a laughingstock.”

Rep. Laura Bradford, R-Collbran, was the lone lawmaker from the region who did not agree to co-sponsor the measure. She said that’s not because she doesn’t support it. She just wasn’t asked.

“This is a good step in trying to avoid any more conflict in the Constitution,” Bradford said. “Finally, businesses are saying they’re tired of writing checks? Good.”